1. Field of the Invention
The present invention relates generally to processing printed products and more particularly to a method and a system for manufacturing printed products, such as books and parts thereof.
2. Description of the Related Art
Current technologies for folding paper for manufacturing printed products are based on buckle folders, plow folding, knife folding, or a combination thereof.
For buckle folders, the paper sheets are fed into a folder (either in line from the printer, but in most cases in an offline process). Generally, there are two folding processes in use. In the first case, the first fold is 90 degree, across from the paper flow. The next one or two folds are in the direction of the paper flow. With this type of fold, one cannot obtain a flat signature. The first fold is against the paper flow, making it uneconomical to perf the paper in this step. Perfing the sheet (across the web) prior to the initial fold, is also not economical, and will still result in a paper stack that is not as flat. Cutting the signature after folding is another option, but would result in the cost of an additional step and wasted paper.
The other option is to use a buckle folder with a parallel fold. On a parallel fold, the perforations can be performed as an extra step, before or after cutting, but the paper has to change direction before folding. The fastest folders in existence, cannot change the direction of the paper fast enough to account for the speed of the highest speed printers.
Another concept is to use a plow fold, which is on a web, but the equipment needs to be stopped and reset to change to another size paper. On a plow folder, the paper can be perfed in line prior to cutting. The paper goes over one or two upside “plows”, and the paper is cut after it is folded. The plow folders allow for high speed folding, but require the folder to stop before the format size can be adjusted, because the process is interrupted. The plow folders require the folding occur prior to the cutting, which makes on the fly changes impossible.
A knife folder is typically used in combination with a plow folder or a buckle folder. In combination with a buckle folder, the same problem of not being able to perf the initial fold exists. In combination with a plow folder, the same problem of changing format sizes exists.
None of the existing technology allows for the creation of a flat signature, with multiple formats, at a high speed. In addition, most of the existing solutions do not allow for folding along the preferred grain direction and do not allow for different cut lengths on the fly.
U.S. published patent application US 2003/0044260 A1 discloses a method and a device for manufacturing books, in which a paper web of a given width is uncoiled from a reel and printed on both sides in a digital printing device. The printed web is then provided with a longitudinal fold extending parallel to the conveying direction. Subsequently the paper web passes through a transverse cutter in which the web is cut into individual sheets. The sheets are supplied to a transverse folding station and provided with a fold extending transversely to the conveying direction of the sheets. The transversely folded sheets are then moved through a longitudinal folding device in which the sheets are folded parallel to the direction of movement.
The printed and folded sheets are fed to a collecting device in which the sheets are collected to book blocks. These book blocks are supplied to an adhesive binding station for adhesively binding together the sheets of a book block at the spine.